1. Field of the Invention
The present invention relates to an exhaust emission control system in an outboard engine for propelling a boat.
2. Description of the Prior Art
There is conventionally known exhaust emission control systems for an outboard engine system, in which a catalyst is mounted in the exhaust system of the engine to purify the exhaust gas by oxidization and reduction (for example, see Japanese Patent Applications Laid-Open Nos. 6-159054 and 4-260893).
In general, in an engine for an outboard engine system, an exhaust passage provided in the engine block of the engine and on a mounting member for mounting of the engine block, may be formed in a straight configuration in a few situations because of limitations in manufacture, structure, function and the like, or may be formed into an inclined configuration, a curved configuration or the like in many cases. Particularly, in a 4-cycle engine, the tendency to define the exhaust passage in an inclined configuration, a curved configuration or the like is great because of the need for defining an oil passage in the engine block of the engine and the need for mounting an oil pan. Further, the shape of the exhaust passage is varied depending upon the form, type and the like of the engine.